The extension to B in Dia 8 is always a good move when Black has
made the high fourth line shimari (enclosure) as shown. When at the same
time it prevents White from making his ideal extension to the same
point, as here, it is doubly valuable.

In a minority of cases C is the better move. Both B and C are still
excellent moves is one or both players have made a low shimari, eg if
the marked black stone were at D or E instead.

This is the well known "crane's nest". Black can capture
three white stones, thus connecting all his own together, if he is
prepared to sacrifice a stone at F in Dia 9. The rest of the sequence is
left for you to work out!

If your answer was I in Dia 10, you were hoodwinked. White can kill
you with the hane at K, followed by J if you defend at L. Black can now
capture both J and K, but not in such a way as to make two eyes.

The only way to live is with J in Dia 10. Dia 11 shows the worst
White can do, leading to a seki (stalemate) after White 5. But as he has
to give up sente to take just five points of territory from Black, and
as Black 2 and 4 may help to reduce some outside white territory, this
is very much an endgame sequence.

Incidentally, this position is discussed in Chapter 9 of "Life
and Death" by James Davies. All you people who waste your time
trying to memorise joseki would do far better to memorise as much of
that book as you can.

By now you will have spotted that the theme of this article is
symmetry. All the solutions so far have beem examples of the Go proverb
"If the formation is symmetrical, play in the centre" ( see
"Go Proverbs Illustrated" by Kensaku Segoe, p50).

You may therefore have chosen M or N in Dia 12 as your solution. If
you did you were hoodwinked again. This position is the odd one out. By
playing asymmetrically at O or P, Black easily links his two eyes
together and all his stones are alive.

If he starts at M, White sacrifices a stone at O. Black can then save
only one half of his group with the sequence Q, P, N, R. If he starts at
N, he can again save half, or fight a ko for the whole group after white
Q, black O, white R, black P, White takes ko at M.